Hip dysplasia is unfortunately found in almost all breeds, especially the larger ones.
The Leonberger is no exception. Hip dysplasia (HD) is an hereditary developmental disease.
HD is a result of abnormal development of the "ball-and socket" joints of the hips.
Severity covers a wide range from slight abnormality to very severe dislocation.
Dysplastic dogs are born with normal hip joints which undergo changes as the dogs mature.

Although the cause is hereditary, the disease can be made worse by environmental factors such as rapid growth, overfeeding and excessive exercise.
Keeping the incidence of the disease to a minimum depends on accurate X-ray diagnosis, accurate breeding records and strict breeding regulations.

The national Leonberger clubs have been extremely diligent in education and enforcement of breeding regulations designed to minimize dysplasia in Leonbergers. Leonbergers are not allowed to be
bred in most countries, without certification that the parent's have hipscores are within the range of the club's breeding rules.

Different countries have different scales for reporting the results of veterinary examination of X-rays.

Note: Not all FCI coutnries devide A and B into A1,A2, B1,B2